MiG-17 in Vietnam

The MiGs encountered in Vietnam came in three varieties: models -17, -19, and -21. The MiG-17 has served in at least twenty fellow-traveling air forces around the world since its operational debut in 1953. It was probably the most numerous aircraft in the NVN inventory, for over half of all MiG kills were -17s.

NATO’s code name for the -17 was Fresco, but regardless of what it was called, it packed a potent battery: a 37-mm cannon and a pair of 23-mm guns in the nose, with the option of heat-seeking Atoll missiles. However, most -17s encountered over North Vietnam were straight cannoneers. Some—not all—were equipped with afterburning engines, rated at 7,500 pounds thrust in a 13,000-pound loaded airframe.

The -17’s distinctive high stabilizer was inherited from the Korean War vintage MiG-15, and in the era of infrared missiles, the Mikoyan configuration provided an unexpected benefit. From almost any angle above the MiG, that high stabilizer partially blocked the IR source, acting as a heat shield.

There were other advantages. With a wing area of some 277 square feet, the -17’s wing loading was only about 47 pounds per square foot. That meant unexcelled maneuverability. If the MiG pilot were half awake, there was just no way to turn with him. Consequently, American pilots fought the -17 in the vertical most of the time, using superior speed and acceleration to gain separation and outclimb the opposition, then coming back in “yo-yo” maneuvers. Crusaders could out-turn MiGs at high airspeeds, in much the same way that Grumman F6F Hellcats outmaneuvered nimble Japanese Mitsubishi Zeroes in the Pacific during World War II. Above 200 knots, the big Grumman’s superior control response remained effective, while the Mitsubishi’s ailerons became semirigid under heavy aerodynamic loads. It was the same over North Vietnam. The drawback was that most jet combats occur at airspeeds under Mach 1, and F-8s could not always rely upon favorable circumstances.

Furthermore, a missile hit or well-aimed burst on a MiG couldn’t guarantee a kill. One MiG killer, Lieutenant Commander Bobby Lee of VF-24, recalled, “For the first few years of the war we used an air-to-ground ammo combination (mostly high explosive) instead of air-to-air (armor piercing and high explosive mixed). With the former mixture we had a couple of gun engagements where the MiGs were damaged by hits in the wings and fuselage, but the HE would skin burst and not kill the engine or vital systems. The MiG is a very tough airplane.”

The MiG-19 was largely an also-ran in the North Vietnam air war. Never engaged in large numbers, it had generally better performance than the -17, but lacked some of the Fresco’s cut-and-thrust qualities. The main armament was cannon. Only ten MiG-19s were destroyed during the war (eight by the air force and two by the navy), and apparently Crusaders seldom tangled with them.

MiG-17

OKB Mikoyan-Gurevich had produced the USSR’s first jet fighter, the MiG-9, in 1946 using a conventional straight-winged airframe and engines based on German samples discovered when Soviet troops captured the BMW and Junkers Jumo factories in 1945. Two copied BMW 003 turbojets enabled the hastily produced fighter to reach 467 knots, carrying an enormous 57mm cannon and two 23mm guns in its nose. Production aircraft, with one 37mm and two 23mm guns (as in the MiG-17) were ordered immediately, but problems with the early jet soon became obvious.

At speeds above 270 knots it was impossible for the pilot to bail out as there was no ejection seat. When all three guns were fired at altitudes above 24,000ft, both engines usually surged and flamed out. The lack of airbrakes, cockpit pressurisation and engine fire-suppression equipment were also symptoms of Premier Josef Stalin’s desire to push the aircraft into service too quickly. Indeed, the MiG-9’s only real advantage over contemporary piston-engined designs was a higher top speed.

Typically for a Soviet design, a large number of prototypes were built around the basic MiG-9 to test two-seat configuration, different armament fits, nose-mounted radar, rocket power and, in 1947, one of the 25 Rolls-Royce Nene centrifugal turbojet engines sold to the USSR by a British Labour Party-sponsored trade delegation in 1946. Prior to the sale, Artem Mikoyan and engine designer Vladimir Klimov had actually visited England to study the engine. Considerably more advanced, and reliable, than the copied German turbojets that powered the MiG-9, the Nenes were swiftly reverse engineered for Soviet production as the RD-45 (later Klimov VK-1).

Ultimately, the Nene-powered MiG-9 was never completed, for OKB MikoyanGurevich had turned its attention to a far more exciting design by early 1946. The appearance of its MiG-15 in the skies over war torn Korea almost five years later was as big a shock to the air arms of the United Nations as the arrival of the Mitsubishi A6M Zero-sen had been to the Allies in the Pacific War in December 1941.

In March 1946 Stalin had challenged his aircraft designers to create a new fighter that was far in advance of the types produced immediately post-war, demanding an interceptor with a top speed of 620mph, a ceiling of 46,000ft and rough-field operating capability. The lack of a suitable engine was solved by the Nene copy, and the crucial, German-inspired, swept wing was chosen after wind-tunnel tests.

The MiG-9’s missing ejection seat, airbrakes and cockpit pressurisation were remedied and hydraulic boost was added for the first time to the ailerons in an otherwise mechanical flight control system. The detachable rear fuselage, inspired by Lockheed’s contemporary F-80 Shooting Star, gave quick access to the engine, while a clever gun tray (like the one subsequently fitted to the Hawker Hunter) housing all three weapons, and their ammunition, could be lowered on a built-in hoist. The choice of guns was, once again, a single N-37 37mm cannon with 40 rounds and two NS-23s 23mm cannons with 80 rounds apiece. Two 260-litre slipper-type drop tanks under the wings added enough fuel to give the MiG-15 a maximum overload range of 1,100 miles.

Like its predecessor, the new fighter was rushed into production and experimental sub-variants proliferated. One tested the faster-firing NR-23 cannon, while others had radar noses, twin seats (ultimately built as the MiG-15UTI, examples of which comprised almost half of the jet’s total 5,000+ production run), ground attack pylons for ordnance (MiG-15ISh) and the afterburning VK-1F engine that would subsequently be used in the MiG-17. During the Korean War, the improved MiG-15bis flown by Soviet, North Korean and Chinese pilots demonstrated superior climb and turn rates and a higher operational ceiling than the USAF’s F-86E Sabre. Against straight-winged types like the F-80, F-84, F9F and Meteor, the MiG had every advantage.

When aimed accurately (fortunately a fairly rare occurrence), its heavy, slow-firing cannon, designed to be used against bombers, could hit targets at longer range than the Sabre’s six 0.50-in. machine guns. Despite this, the much better trained USAF pilots, many of whom had World War II fighter experience to draw upon, used their more reliable and better-equipped fighters to score a kill/loss ratio of at least 4-to-1 against MiG-15 pilots.

The MiG-17, on which design work began in 1949, was intended to correct any problems revealed during the MiG-15’s combat debut. Production was delayed by the pressure to manufacture more MiG-15s for combat, and the new fighter did not enter service in the USSR until October 1952 – by which time the appreciably faster MiG-19 was on the verge of commencing flight testing. Referred to originally as the MiG-15bis45, the revised design changed the MiG-15’s 35-degree constant wing sweepback to a compound 45-degree angle (like the North American F-100 Super Sabre) up to the mid-span, and 42 degrees for the rest of the wing. This was called a “sickle” sweep, and it was less radical than the “crescent” wing used on the Handley Page Victor bomber, for example.

Like the MiG-15 “Fagot” (NATO reporting name), the new design was to be a lightweight, simple and reliable machine that would continue the tradition of the “samolyot-soldaht” (“soldier aircraft”). While using much of the MiG-15’s structure, the new design sought to remedy some of its shortcomings. The new wing improved the lift-to-drag ratio and overcame the MiG-15’s tendency to dip a wingtip unexpectedly at high speed because the structure was not stiff enough to maintain aerodynamic symmetry under high wing loads. Flight controls, avionics and armament remained virtually unchanged, but the tail section was altered, with a larger vertical tail and a 45-degree rather than 40-degree sweep to the horizontal surfaces.

The MiG-15bis45 (SI-1 prototype) crashed on March 17, 1950, probably as a result of “flutter” tearing off the horizontal tail. Aileron control reversal at high speed due to a lack of wing stiffness (a common problem in early swept-wing jets) was also discovered and remedied.

With so many changes to the MiG-15 design it was clear that a new designation was the summer of 1951. The fighter was ordered into production before those trials had been completed, and service evaluation began at Krymskaya air base, in Crimea, before year-end. Shortly afterwards it was given the NATO reporting name “Fresco-A”.

Soviet pilots found the aircraft stable, but slightly heavier on the controls than the MiG-15. The airbrakes from the latter soon proved to be too small, the undercarriage brakes inadequate and the elevator actuators underpowered. Test pilots also advocated a stability augmentation system as used in Western fighters, but none was available. However, pilots did get a safer ejection seat with a Martin-Baker style protective face curtain and leg restraints in 1953. A clear-vision canopy without the heavy rear frame was designed, but the cheaper option of a rear-view periscope was installed in production MiG-17Fs. After the capture of a USAF F-86A Sabre in 1951 in Korea, Soviet engineers copied its optical gunsight and gun ranging radar, which subsequently appeared as the ASP-4N gunsight and SRD-3 gun ranging radar in test-bed MiG-17s from October 1952. These systems were later introduced to production aircraft in modified form.

The most significant improvement came with the availability of the VK-1F afterburning engine, which was the first effective Soviet unit of its kind. The basic Nene-inspired VK-1A was at the limit of its development by 1951, and afterburning was the only way to increase the thrust output of the turbojet engine. In the MiG-17F (the “F” indicated “afterburning” in both engine and aircraft designations), a modified rear fuselage accommodated the convergent-divergent engine nozzle and the fuel system was modified.

Testing showed that the new engine made supersonic flight just about possible in a shallow dive. It also doubled the fighter’s rate of climb and made vertical manoeuvres during dogfights far easier to perform. It yielded little improvement in horizontal speed, however. Just short of Mach 1, the aircraft would suddenly pitch up and the available elevator stick forces were not enough to prevent this.

The need for an all-weather version of the MiG-17 meant that the second “Fresco-A” development aircraft (SP-2) was immediately used to test the “Korshun” radar in a bullet radome above the intake. From 1952 onwards, testing of the MiG-17P with an Izumrud RP-1M radar in place of the “Korshun” began, and this variant was eventually placed in production as the USSR’s first lightweight radar equipped interceptor – the “Fresco-B”. This was followed in May 1953 by the “Fresco-D” (MiG-17PF), which received the more powerful Izumrud RP-2 from December 1955. The installation of a search radar did not free the MiG-17PF from reliance upon Ground Control Interception (GCI), however.

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